You can also use the command-line of libreoffice for your purpose. That gives you the advantage of batch conversion. But single files are also possible. This example converts all ODT files in the current directory to PDF:

libreoffice --headless --convert-to pdf *.odt

Get more information on command-line options with:

man libreoffice

(Note: Due to bug 37531, you have to close all running instances of LibreOffice before this command will work.)

Another argument for command line usage is that for instance in my case the gui has all of a sudden started producing flawed pdf's, but the command line still works like a charm.
–
Hermann IngjaldssonFeb 27 '13 at 14:16

1

Thi9s works, but it has a problem: if the GUI is open the command will do nothing (not even show an error). Ugly, but with this workaround you can open a new instance: --env:UserInstallation=file:///path/to/some/directory.
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toklandSep 16 '13 at 13:14

Note: I decided to delete my answer from this question and to post a modified version of it here when I realised that unoconv doesn't deal with psw files at all well, and doesn't convert them successfully to other formats. There may also be problems with docx and xlsx formats.

However, Libreoffice fully supports many file types; full documentation is available at the official site, which details the valid input and output formats.

You could use the command-line libreoffice convert utility or unoconv, which is available in the repositories. I find unoconv to be very useful, and it is probably what you want. Even though Takkat has briefly mentioned unoconv, I thought it would be useful to give some more details and a batch conversion one-liner.

Using the terminal you could cd to the directory containing your files and then batch convert all of them by running a one-liner like this:

for f in *.odt; do unoconv -f pdf "${f/%pdf/odt}"; done

(This one-liner is a modification of my translate script featured in this answer.)

If you later want to use any other file formats, just substitute the odt and pdf for any other supported input and output formats. You can find the supported formats for a file type by entering unoconv -f odt --show. To convert a single file use, for example, unoconv -f pdf myfile.odt.

Further information on and options for the program can be found by entering in terminal man unoconv or by going to the Ubuntu manpages online.